SUN-003 A Rare Case of Adipsic Diabetes Insipidus as a Complication of Clipping of Anterior Communicating Artery Aneurysm.

Abstract Disclosure: A.U. Kulkarni: None. P. Lekprasert: None. K. Win: None. Arginine Vasopressin (AVP) along with the intact thirst mechanism maintains appropriate sodium levels in the human body, lack of which causes central Diabetes Insipidus (DI). Adipsic DI is a rare entity where the thirst mechanism is disrupted causing lack of compensatory water intake. We present a case of Adipsic DI following ACOM (Anterior Communicating Artery) aneurysmal clipping.Case: A 65yo man with a history of Hypertension presented to the ED with lethargy, headache, blurry and double vision for 5 days. Vitals were notable for elevated BP of 220/110 mmHg with a normal neurological exam. CT head showed 4mm left parafalcine subdural hematoma, and 3cm left ACOM aneurysm. Nicardipine drip for BP management was initiated. Craniotomy with aneurysmal micro-clipping was performed the next day without any immediate intra-operative complications. Post-operatively, during the first night, polyuria was noted with a total urine output of 5.7L, up-trending serum sodium of 139mmol/L (previously 131mmol/L), serum osmolality of 286mOsm/kg, Urine studies showed urine soidum < 20mmol/L, urine potassium of 2.7mmol/L, urine chloride < 20mmol/L, and urine osmolality of 51 (300-1090 mOsm/kg), consistent with DI. On post-op day 2, he suffered multiple acute infarcts causing left-sided hemi-neglect and aphasia. He was treated with as-needed intravenous DDAVP dosing under Endocrinology guidance while monitoring urine output and serum sodium. By post-op day 6 sodium had normalized, and DI was considered resolved. He was discharged to acute rehabilitation, where Adipsia was reported and water intake was monitored. Around post-op day 10, the patient became hyponatremic, likely due to the transition to the SIADH phase. This resolved in 4 weeks from his initial surgery. He was seen in the Endocrinology clinic where he continued to report adipsia. Discussion: Anatomically, the osmoreceptors that regulate thirst overlap with the cell bodies containing AVP in the hypothalamus and share a common blood supply through small branches of the ACOM. Any disruption of this blood supply can lead to Central DI with adipsia. Adipsic DI most commonly occurs as a surgical complication. ACOM clippings account for about 40% of cases followed by resection of large craniopharyngiomas, supra-sellar tumors and infrequently in traumatic brain injury and neurosarcoidosis. Management involves prescribed DDAVP orally or intranasally to target a urine output of 1.5-2L/ day and fixed dose daily fluids to ensure euvolemia. It remains challenging as these patients often experience significant cognitive and memory impairment. Limited information is available about thirst recovery, which could be partial or complete. Recovery can occur over months-to-years with no identified pattern. Thus, we must anticipate and monitor patients undergoing these surgical procedures for adipsic DI to reduce complications of sodium and water balance. Presentation: Sunday, July 13, 2025